Zinc ionomers are known to be activators for sulfur curable compositions. For example, U.S. Pat. No. 8,686,084 to Wilson discloses sulfur curable rubber compositions and cured articles based on the use of zinc activators for sulfur cure.
Zinc oxide is also known to improve the cure rate of rubber compositions, and is commonly added to golf ball compositions in a conventional powder form. Alternatives to conventional zinc oxide powder have been disclosed, for example, in U.S. Pat. No. 6,919,395 to Rajagopalan et al., which discloses golf ball compositions comprising zinc nanoparticles.
There remains a need in the industry for alternative methods of providing zinc activator to curable golf ball compositions. The present invention seeks to fulfill this need with golf ball compositions comprising zinc ionomers. Such compositions may provide one or more of the following benefits: less elemental zinc required for an equivalent state of cure, resulting in lower levels of zinc and zinc extractables than with zinc oxide; product design flexibility, including, for example, allowance for lower densities than with zinc oxide and replacement of zinc oxide with high specific gravity fillers; improved cure profile; and improved durability.